In order to detect the presence of a signal hidden deep in the noise floor, special detection techniques, such as interferometry or radiometry, are required. An interferometer or a radiometer can be employed to detect the presence of a signal in the noise floor by correlating two antenna inputs or one antenna input with itself respectively. Traditional interferometers and radiometers are only capable of instantaneously processing a narrow spectrum (e.g., 100 MHz). The primary reason for this limitation is that these traditional techniques repeatedly compare (or correlate) a slice of one antenna input to a series of slices of the other antenna input in an attempt to identify a match. The number of comparisons that would have to be made to simultaneously process a wide spectrum becomes prohibitive.
When it is necessary to search for a hidden signal over a wider spectrum using the traditional techniques, smaller portions of the spectrum can be processed serially. In particular, the spectrum can be divided into portions and then each portion can be processed one at a time such that, at any given time, only a small portion of the spectrum will be examined for the presence of the hidden signal. If the hidden signal happens to appear at a frequency that is not with the portion currently being processed, the system will not detect its presence. Therefore, at best, these traditional techniques are inefficient for detecting a hidden signal within a wider spectrum, and at worst they may be incapable of detecting the signal.